1. Field of the Invention
The present invention relates to a cathode ray tube (CRT), and more particularly, to a funnel having a neck portion in which an in-line electron gun is installed, and a cathode ray tube adopting the same.
2. Description of the Related Art
Referring to FIG. 1, a typical CRT includes a panel 12 coated with a fluorescent film 11, a funnel 14 which meets the panel 12 and has a neck portion 13, and an in-line electron gun 15 installed in the neck portion. The CRT further includes a deflection yoke 17 which is mounted over the cone portion 16 from the neck portion 13 of the funnel 14 and deflects an electron beam which is emitted from the electron gun 15.
As shown in FIG. 2, the electron gun 15 includes a cathode assembly 15a arrayed in an in-line shape for emitting thermal electrons, and a plurality of electrodes 15b fixed to a bead glass 15c. Three electron beam passing holes are formed through each of the electrodes 15b in an inline shape.
In the operation of the conventional color CRT having such a configuration, electron beams emitted from the electron gun 15 are selectively deflected by the deflection yoke 17 according to an image signal. Deflected electron beams land on a fluorescent film and excite the fluorescent material thereon, thereby forming a picture.
The electron gun 15 is sealed and installed in the tube-shaped neck portion 13 such that electron beam passing holes are horizontally arrayed, thus forming a difference between the horizontal deflection force of an electron beam and the vertical deflection force thereof. Also, it is preferable that the interval between the center of a middle electron beam passing hole (hereinafter, a deflection center) and the inner circumferential surface of the deflection yoke is narrowed, since a voltage to be applied to the deflection yoke can be reduced. However, since the neck portion having such a configuration has limit in narrowing the interval, a high voltage should be applied to a deflection coil of the deflection yoke to obtain a desired deflection of an electron beam.
The interval between the deflection center and the inner circumferential surface of the deflection yoke can be narrowed by reducing the diameter of the neck portion 13. However, this reduces the diameters of the electron beam passing holes formed through the electrodes of the electron gun 15, which consequently increases the spherical aberration of an electron lens which is formed by the electron beam passing holes, thus degrading the focusing characteristics of an electron beam.
In particular, about 96% of power consumed by a color CRT is consumed by the deflection yoke, among which about 71% is known to be consumed to horizontally deflect electron beams. Thus, the distance between the horizontal deflection center of the deflection yoke and the deflection center of an electron beam must be narrowed to reduce the power consumption of the deflection yoke.
Also, since the electron beam passing holes are horizontally arrayed through each of the electrodes 15b of the electron gun 15, the electrodes are horizontally long, such that spaces are formed on the upper and lower portions within the neck portion. These spaces increase the exhaust process time for vacuumizing upon the manufacture of a color CRT.
To solve the above problems, an objective of the present invention is to provide a funnel which can reduce unnecessary spaces within a neck portion and improve the deflection sensitivity by narrowing the interval between a deflection yoke and a deflection center.
Accordingly, to achieve the above objective, the present provides a funnel for a color cathode ray tube (CRT) including: a neck portion whose cross section is vertically long; a first cone portion which extends from the neck portion such that the cross section is vertically long as the neck portion, and is surrounded by a deflection yoke; and a second cone portion which extends from the first cone portion to be enlarged and meets a panel.
Here, the lateral surfaces of the neck portion, which are parallel to the longitudinal direction of the neck portion, are flat, and the upper and lower surfaces are curved.
According to a different aspect of the present invention, there is provided a color cathode ray tube including: a funnel including a neck portion whose cross section is vertically long, a first cone portion which extends from the neck portion such that the cross section is vertically long as the neck portion, and is surrounded by a deflection yoke, and a second cone portion which extends from the first cone portion to be enlarged and meets a panel; an electron gun which installs within the neck portion, and has a plurality of vertically-long electrodes through which electron beam passing holes are longitudinally formed with respect to the cross section of the neck portion; and a deflection yoke installed over the neck portion and the first cone portion, for deflecting electron beams which are emitted from the electron gun.